WASHINGTON -- Democrats in the U.S. House of Representatives plan to introduce legislation that would require presumptive Republican presidential nominee Mitt Romney to release 10 years of tax returns, along with other personal financial information.

The legislation, which will be introduced by Rep. Sander Levin (D-Mich.), is specifically aimed at presidential candidates with complex and secretive financial holdings -- much like the former governor of Massachusetts. It would require candidates to disclose information "not currently included on disclosures and not easily discernible from tax returns," and would help "provide a fuller picture of a candidate's financial holdings and interests," according to a press release Wednesday from the House Ways and Means Committee.

Romney has repeatedly refused to release more than two years of tax returns, despite pressure from the Obama campaign and a rising chorus of Republican leaders, such as Mississippi Gov. Haley Barbour and former GOP Chairman Michael Steele.

Levin's legislation would also require the release of more information on assets held in IRAs, 401(k) plans and other tax preferred accounts, and would force the disclosure of any ongoing compensation received by the candidate.

"The stunning lack of transparency from someone in pursuit of the highest office in the country highlights the need to change the law to require fuller disclosure," Levin said in a press release Wednesday morning. "For decades, presidential candidates have voluntarily provided a thorough accounting of their tax returns and finances, as they should. But we clearly cannot continue to rely solely on the willingness of a candidate to disclose fully what the public has a right to know about the candidate’s financial record."

On a conference call Wednesday afternoon, Levin told reporters that he hopes to formally introduce the legislation before the congressional recess in August, hopefully with Republican support.

This story has been updated to include a quote from Rep. Sander Levin and information from an afternoon press conference.